I have an 88 FC with an S5 VDI Manifold. I was attempting to replace the thermowax and in doing so tried to take off the throttle body. After taking it partly off, I got an urgent phone call and tried to put it all back together. After putting everything back together, all vacuum hoses reinstalled, I try to start the car and it dies immediately. It starts really smooth and then just dies instantly. I have spent over an hour checking and re-checking everything to make sure I put it all back together properly. Could it be something with the airflow throught the throttle body to the upper manifold? The screw mounts align it perfectly but could it possibly be off just the slightest bit?? What else could it be??

 

Sounds like you unplugged the AFM's electrical connector and didn't plug it back it.

 

do you mean the thing that plugs into the air flow meter? I did plug that in unless your talking about something else...I will take a better look at it when it's light out.

 

most likely ECU is going into fail-mode (something major is disconnected, i.e. AFM), or you have a very large vacuum leak somewhere. check all connectors and hoses again. make sure your throttle plates are in proper position also.

 

Hey guys so I went out to try and troubleshoot the car, took off my intake elbow, and I noticed that the throttle plates are closed...I don't think this is normal. Logically as the engine is getting no air it isn't going to idle. The only plate that is open is the one closest to the elbow. The two rear plates up top and the rear bottom one...are all closed. 3 of them in total. Is this my problem? And if so, how do I fix it?

 

not yoru problem. did you plug in the 2 hoses that are connected into the intake tube? that woudl be a problem. but as a matter of fact my car is doing the EXACT same thing. i can start it fine and keep it running as long as i play with the gas but if i let the pedal go it dies like your saying. cant keep an idle at all. no idea. if it was running find before (mine was to) then i dont know what to tell ya

 

yeaah...i connected those hoses...the car will start get to 3000 rpm for a second ....then drop down and die....I am stumped...

 

I'm thinking it could be my fast idle system at fault...as it opens the primary throttle valves slightly at idle allowing the car to idle when it's cold. Which we are substituting with throttle. The manifold has enough air for the car to start but as the air pressure goes below atmospheric, the car dies.

 

I've tried starting the car so many times, that the battery I believe is now dead. The car doesn't even crank when I turn the ignition. That is the battery am I correct...I feel so stupid for screwing around with something that I just shouldn't have touched.

 

well before i bought the motor it ran fine. it was in the guys car and i watched it pulled out. then i put a OMP with the lines on it and ever since it wont idle. there are few times it will idle at 4-5k and then when it gets about 3k it dies. so far ive changed out the MIM, LIM, TB, MAS, ECU, checked for leeks many of times, and aint gotta clue. hope you get it running again. good luck with it. if i get my problem solved ill let you know and see if it works for you

 

I mean the electrical plug. If it's not connected properly the engine will start fine then die. If that's okay, it sounds like a big vac leak.

The throttles are always closed when your foot's off the pedal. That's how every petrol engine in the world works. There are bypass passages to allow for idle air.